Ageing of the hematopoietic niche in a short-lived vertebrate

This thesis aims to investigate the cellular and molecular mechanisms underlying the aging of the immune system, focusing on the main hematopoietic organ of the teleost fish Nothobranchius furzeri, a model animal used in the study of aging. First was developed a new functional assay that allowed to quantify the immune response. This assay has been experimentally validated and applied in particular to immune cells extracted from the hematopoietic organ (the head-kidney) in young and old fish, highlighting significantly different immune responses between these two conditions. In order to understand the cellular and molecular basis of these differences in the immune phenotype first was used Fluorescence Activated Cell Sorting (FACS), which shows a significant expansion of the population of myeloid cells within the kidney in old killifish compared to the young ones. Subsequently, by immuno-histo-chemistry was measured a slight decrease in the proliferative signal within this organ during ageing, which, however, increases in very old fish. Finally, by combining original single-cell RNA Sequencing data generated in the Valenzano laboratory with Real-time PCR, proteomics and metabolomics techniques, were investigated at the molecular level the differences occurring during aging in the immune cells resident within killifish head-kidney. These analysis highlighted in elderly fish the establishment of a chronic oxidative and inflammatory stress, a decline of protective mechanisms like autophagy, DNA surveillance/repair or antioxidant systems, a reduced proliferation activity of the stem cells/progenitors and at the same time an increase of myeloid differentiation inducers